This invention relates to a process for measuring the draw-in force at the interface between a tool and the spindle end of a machine tool. The invention also relates to a device for carrying out the process, and to a gauge for adjusting the device. Excessively low draw-in forces of the tool holder in the machine spindle can entail considerable costs. Measurements have shown that the draw-in forces often lie well below the nominal values. This can have serious consequences as a result. Only a sufficient draw-in force permits the complete utilization of the drive force. Large draw-in forces make a large machining capacity possible, while small draw-in forces only permit small feeds and shallow cutting depths.
Sufficiently great draw-in forces are in general particularly important if the tools are stressed radially (laterally).
This is above all the case during milling. During this operation, oscillations (vibrations) arise as a consequence of interrupted cutting. Lateral forces, with simultaneously occurring vibrations, are not conducive to a steep-angle cone connection. The connection loosens, and the tool is "squeezed out".
An insufficient draw-in force has as its consequence the occurrence of vibrations during milling, and can, under certain circumstances, have devastating effects, with fretting corrosion occurring on the steep cone; the boring of the machine spindle can even be damaged.
The draw-in force is determined, in machine tools with an automatic change of tools, by a draw-in device positioned in the spindle. The supplier of the machine specifies the draw-in force which will be produced, by means of a spring or a set of disk plates, for example. When setting up a new machine, it is always advisable to check the prescribed draw-in force before beginning operation. Even later during operation, however, if the work pieces being processed show slight signs of rattling, it is advisable to again further examine the draw-in force. After a certain operating period, it is even possible to carry out this examination on a routine basis. Such a measuring process could not previously be carried out, however, since the means necessary for this were lacking.